WASHINGTON, Feb 2 (Reuters) - The U.S. Justice Department is seeking “substantial” civil fines from Fiat Chrysler Automobiles NV after the government filed suit accusing the company of illegally using software that led to excess emissions in 104,000 U.S. diesel vehicles sold since 2014, a person briefed on the matter said Friday.

Bloomberg News reported Friday that the Justice Department sent Fiat Chrysler lawyers a Jan. 27 settlement offer that included requiring the company to offset excess pollution and take steps to prevent future excess emissions.

A person briefed on the matter confirmed the letter included language that a settlement “must include very substantial civil penalties.”

At a discussion in Washington last week between the Justice Department and Fiat Chrysler overseen by court-appointed settlement adviser Ken Feinberg, no specific figures were discussed, two people briefed on the talks said. Another round of settlement talks is set for late this month.

Feinberg and Fiat Chrysler declined to comment.

In July, Fiat Chrysler won approval from federal and California regulators to sell 2017 model year diesel vehicles after it came under scrutiny for alleged excess emissions in older diesel models.

To resolve the excess pollution issue, Fiat Chrysler lawyer Robert Giuffra said in December at a court hearing the company remains confident it can use updated emissions software in the 2017 vehicles as the basis of a fix to address agencies’ concerns over 2014-2016 diesel vehicles.

The Justice Department said in December that company testing on the proposed fix began on Dec. 17 and would take about three months. The government will then have 30 days to review the results and expects to make a determination by the end of April.

Regulators have said Fiat Chrysler diesel vehicles had undisclosed emissions controls that allowed vehicles to emit excess pollution during normal driving. The company has denied wrongdoing, saying there was never an attempt to create software to cheat emissions rules.